Steps to BPU

Can i make my first step to BPU as purchasing a FCD? Or would it make no difference with no decats, no new plugs etc.

you will need it, if not yet

Assuming you have a J-Spec, the cats will control your boost to 0.8 bar.

But I wouldn't want to risk, incase of overboosting (for whatever reason - colder denser air in the morning) with your cats still in - because of the EGT's.

Ok so first step is decat then i guess.

Ok so first step is decat then i guess.

Assuming you have a Jspec then no!

Decat is the LAST thing to do.

1st Good service inc fuel filter

2nd Aftermarket catback

3rd Fuel pump and FCD (you need these before raising boost)

4th Boost gauge

5th Decat, restrictor ring and plugs

1-3 have to be in place before the decat, boost gauge isn't essential but highly recommended

Nice one Homer, that puts things in perspective. I am indeed JSpec.

So catback does more restriction than the front?

No problem mate.

The cat-back section is restrictive but no where near as much as the front 2 cats. That's why its safe to replace it before the other mods as it will only let the boost raise a little above stock.

thats useful to know!

my j-spec boosts to 1.1 and has both cats and no boost controller???

may try changing the boost gauge in case of a fault

The cat-back section is restrictive but no where near as much as the front 2 cats. [/Quote]

 

Im confused is there 3 sections? Thought it was just 1 cat at front one cat at back.

2 in a row at the front, then the cat back exhaust

We got any exhaust diagrams here lol?

Oh i see. I was asking a while back what this thing was. Is this the catback? Its just after the exhaust, and has the same Kakimoto writing as my exhaust. If this is the case I guess I am 1 step further!

That does indeed look like a Kakimoto exhuast, so you won't need to replace that. If you look further down the pipe to you'll see the stock 2nd cat.

The Kakimoto is a nice sounding exhaust too, theres not many of them around.

So this is my catback?

Yea its a weird exhaust, its really wide at the opening, but you can see its a smaller pipe inside. I hope this wont affect it for being BPU, i guess you want them wide as possible.

Yes, thats a "cat back" (i.e. behind the catalytic convertor)

Some exhausts are just like that, big shiney pipe on the end with a smaller silencer.

It could still have a baffle in it, got any shots of the backbox?

Ill go take one now for you sir

I have an hks ti cat back system to fit to my gz tt when it gets here from japan it has got a boost gauge what sort of boost would i expect to get (both cats in place)

Heres some pics

Heres some pics

Ah, now thats not a Kakimoto, looks like someone has screwed a shiney pipe on the end of a generic aftermarket exhuast. Its probably not the best system for BPU but should work if both silencers are straight through. You don't actually need anything bigger than 2.5 diameter for BPU, but all aftermarket cat backs will be 3inch+

I have an hks ti cat back system to fit to my gz tt when it gets here from japan it has got a boost gauge what sort of boost would i expect to get (both cats in place)

Probably not more than 0.8 bar with both cats in, though its far from an exact science. Different cars give different results and boost will change with weather (pessure and temp).

Probably not more than 0.8 bar with both cats in, though its far from an exact science. Different cars give different results and boost will change with weather (pessure and temp).

Kewl thanks m8.

Whats stock boost m8

Kewl thanks m8.

Whats stock boost m8

Good question, not sure anyone here has ever seen it I'd take a guess at 0.7 bar.

Close .. 0.8

Close .. 0.8

Yeah you're right. just looked in up in the manual its 11.9 psi (0.83 bar). Never knew that before

then how is mine so high?! thats worrying!